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screen printing => Screen Making => Topic started by: Racer Tees on March 02, 2015, 12:50:01 PM
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Trying out some Aquasol HVP this week. Been using some Tex Blue from a local supplier. The ink from the film is sticking to the emulsion after exposing. Only thing that has changed is the emulsion. If you reclaim it comes right off. Exposure looks good except for the black ink stuck to it and the otherwise now worthless film.
I'm about a dozen screens into the bucket when this happened. I love it compared to what I had before, but I'm lost on this.
What would cause this?
(https://dl.dropboxusercontent.com/u/175543912/Screen-Film-Ink-1.jpg)
(https://dl.dropboxusercontent.com/u/175543912/Screen-Film-Ink-2.jpg)
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my guess...your emulsion isn't dry enough. I've had this problem with other emulsions, but never HVP
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When we were using films this happened to us alot. We still couldn't really find the source of it, aside from possibly the humidity in our ink room, or the films getting to hot while exposing.
for us it was happening on screens that had been sitting upwords of a week before being exposed!
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I was thinking someone was gonna say humidity. I'm at like 55% humidity in my screen box. Might be time for a Dehumidifier?
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ours was at 40% and it was still happening
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Small heater in dry box and dehumidifier in the room. Should help?
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IMO it is caused by heat from the bulb coupled with whatever humidity is in the emulsion. The day I went LED the problem immediately went away with very few exceptions of a freshly coated 110
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Still happened to me even after I built my new screen room which is a constant temp of 72-78 degrees and 35-40% humidity, even if the screens had dried for a month and the films had been left in the same room. Happens more on thicker stencils/lower mesh.
SP1400 I can coat, dry for 20 minutes, and expose without issue. Longer exposure of course.
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IMO it is caused by heat from the bulb coupled with whatever humidity is in the emulsion. The day I went LED the problem immediately went away with very few exceptions of a freshly coated 110
Well. I plan to go LED in the near future.
Still happened to me even after I built my new screen room which is a constant temp of 72-78 degrees and 35-40% humidity, even if the screens had dried for a month and the films had been left in the same room. Happens more on thicker stencils/lower mesh.
SP1400 I can coat, dry for 20 minutes, and expose without issue. Longer exposure of course.
What is your exposure time difference from HVP to SP1400?
This literally just came off the exposure unit. Washed out perfectly.....
(https://dl.dropboxusercontent.com/u/175543912/Screen-Film-Ink-3.jpg)
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I have had this issues with films fairly fresh off of the printer, and certain emulsions that just seem "tackier" than others. (These same emulksions also tend to reclaim more like bubble gum)
Band-aid fix is lightly dusting with talcum powder.
On the other hand, many don'r even bother to catalog films any more with output being so easy (compared to the days of stat cameras) So, as long as a screen works, the damaged film may not be as much of an issue.
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I don't mind the damaged film as it's not a big expense. But these designs will be reprinted about once a month all year....
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"Proper" exposure time is a little less than double for SP1400 on my setup, though for plastisol runs I can expose them almost the same honestly and have no issues, but it isn't a full exposure. I run lots of discharge though and prefer to just have single times per mesh/coating vs switching it up at random and possibly running into an issue. I have found with the 1400 I can expose it a really long time and not see much undercutting or loss even with 55lpi halftones. If I know I'm doing a long run of DC white for example, I will "over expose" just to be sure it has no breakdown. I am using a 1k MH though, so I would expect on something stronger the exposure difference and the need to "over expose" would be different.
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I rub a little talcum powder on all my screens before exposing. It solved that problem for me. My problem was humidity in the summer. It was actually causing the film to stick a little.
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We had issues like this with chromablue, baby powder is what we used?
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I've had it too. A dehumidifier in my darkroom was the fix for me. Even still, if it's raining and I go right from film output to exposure it might still happen. I am convinced it is humidity.
I didn't like talc, but on films I MUST catalog, I've sprayed Krylon Matt Clear on the films with good result. Test on films you can easily reproduce.
To state it again, this problem ONLY happens to me when I'm rushing the films, AND/OR the emulsion isn't dry enough, for whatever reason. Foggy weather has even cause it.
My 2 cents.
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For us here. This problem = rushing/humidity.
Murphy37
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I was getting this a lot. My solution - when you go to print your films, invert the image. Now when you go to expose the print side of the film isn't touching the emulsion. I wasn't sure if that would mess with the image quality, but so far so good.
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Not going to hurt the image just choke it for better term with light undercutting. Less humidity little high dry temp of 90-100 will help. Try to around 20-25% humidity. Is what I have found.
Shane
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Dehumidifer and sticking the films in the dry box when I was using CCI HPV. OrChroma blue I switched to Saati PHU and have never had it happen.
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I wouldn't recommend inverting. for spot colors it will probably be fine unless they touch a lot and on a base it will be worse. Halftones with this method will give you much more gain than you would normally get.
I would fix the problem with too much humidity and do films the correct way.
FYI this is an old school trick for trapping...it dates back a long time.
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FYI this is an old school trick for trapping...it dates back a long time.
You're Kidding!! I didn't know that.
Sure makes sense.
It's humidity though. I've satisfied myself of that long ago. A rainy couple of days back to back can still do it for me.
I've worn out 3 power supplies for my teensy weensy DEhumidifier that sits on the floor in my darkroom. When it quits, I get another one right away. It runs 24/7/365. No more sticking, unless lots of rain and I bring screens out of dry storage too long before shooting them.
Stan
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As far as the trick of "inverting" to avoid the emullsion side of the film, you mean mirroring.
As you can easily see in your graphics program, "inverting" will reverse what is black and what is clear, while mirroring will flip the image, making it right-reading on the back side of the film.
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Humidity problem for us as well. Powder in a Crown Royal bag. Dust every screen prior to taping the films, problem solved.
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dehumidifier in the screen closet
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If you're using silly old-school tricks to keep it from sticking, just put another piece of poly in between the positive and emulsion. :P
(Also works to trap the white on designs from sep impaired artists)
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If you're using silly old-school tricks to keep it from sticking, just put another piece of poly in between the positive and emulsion. :P
(Also works to trap the white on designs from sep impaired artists)
I don't like the idea of flipping the film, but if you are going to do something like that, this sounds like a much better idea. I bet you could find a very think micron sheet to use which would help with the choking issue. And it wouldn't alter your art/film output process.
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Baby Powder
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Fix your humidity problem and dont waste time on gimmicky work arounds that are band aids for the underlying problem. 55% is too much. Our screen room sits around 25% if not lower. The moisture issue can also be in the film if your humidity is high where your films are stored. They are made to attract moisture.
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I put a dehumidifier up in my screen room. Thinking about moving my film storage in there as well.
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Fix your humidity problem and dont waste time on gimmicky work arounds that are band aids for the underlying problem. 55% is too much. Our screen room sits around 25% if not lower. The moisture issue can also be in the film if your humidity is high where your films are stored. They are made to attract moisture.
We hit 25% and still have sticking issues with chromablue.
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Most have hit upon the solution. Talc or Baby Powder, it won't create pinholes. In the tropics you have to use it to avoid the tack issue, w humidity in the 90% range. Usually caused by heat from a Metal Halide lamp in combination with humidity. A little talc preserves all films, especially in shops that expose a lot of screens in an enclosed 5k-6k MH unit. LED's have no heat so less tack. Tack can be useful. We have an emulsion designed to promote tack and film adhesion to shoot better halftones. Great for real film, tough on ink jet films. So the talc does fix this.
Al
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I output film in mirror, ink is not in contact with the emulsion.
I read this is not the best, but honestly I see no difference when exposing critical job like halftone job.
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I output film in mirror, ink is not in contact with the emulsion.
I read this is not the best, but honestly I see no difference when exposing critical job like halftone job.
As has been pointed out, light will sneak through the thickness of the clear film and slightly undercut your open dots.
Perhaps, using this old traditional method of choking, you have also stumbled upon a way to compensate for dot gain. ;)
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I apply a custom curved before sending to accurip.
I will expose the normal way on my next critical job and compare again.
Thank you
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The simple all around fix is to simply use some powder. Simply throw some on the screen and spread it around with your hand to spread and coat evenly the film side of the screen right before exposure.
Controlling the humidity takes more attention, time and energy and you are chasing a seasonal / weather influenced / geographic variable.
We have experimented with over drying screens in a 95- 100 degree environment for 6 hours and the ink still stuck to the emulsion.
We have tried damprid http://www.damprid.com/ (http://www.damprid.com/) in a closed cabinet with coated screens and some ink still sticks.
Remember (at least in our situation) it is not the film that sticks to failure but the ink coating on the film.
Yes our waterproof films did stick to the emulsion in the worst cases but the true damage came when the ink pulled off the film creating a DTS the hard way!!!! ???
Like everyone the issue here in the north east was way worse in the spring / summer than in winter.
the stop drop and roll fix, (in our multi hundred $ business) is simply to stop trying to fix the environment and throw some powder on the darn screen. .......................Just go print something and leave the environmental issues to Al Gore
mooseman